ʿAlāʾ al-Dīn Abū al-Ḥasan ʿAlī ibn Abī Ḥazm al-Qarashī, known as Ibn al-Nafīs, was an Arab polymath whose areas of work included medicine, surgery, physiology, anatomy, biology, Islamic studies, jurisprudence, and philosophy. He is known for being the first to describe the pulmonary circulation of the blood. The work of Ibn al-Nafis regarding the right sided (pulmonary) circulation pre-dates the later work (1628) of William Harvey's De motu cordis. Both theories attempt to explain circulation. 2nd century Greek physician Galen's theory about the physiology of the circulatory system remained unchallenged until the works of Ibn al-Nafis, for which he has been described as "the father of circulatory physiology".

Physiology is the scientific study of functions and mechanisms in a living system. As a subdiscipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out chemical and physical functions in a living system. According to the classes of organisms, the field can be divided into medical physiology, animal physiology, plant physiology, cell physiology, and comparative physiology.